Output most constructors an element at a time.

(digest_init): Deleted code for raw constructors.
(process_init_constructor): Function deleted.
(start_init, finish_init): New functions.
(really_start_incremental_init)
(push_init_level, check_init_type_bitfields, pop_init_level)
(set_init_index, set_init_label, process_init_element)
(output_init_element, output_pending_init_elements): New functions.

From-SVN: r4973